The replies really should be "no, stop wanting that." IRC is not meant for such interactions, and is built around different social expectations. If you want 24/7 presence, then you ought to justify it socially, because there is a qualitative cultural difference between folks who regularly idle on IRC vs. folks who are only connected to IRC when they actively want to discuss something. Similarly, backlogs are only marginally useful and are usually a security risk, but the typical client does offer full-text search through IRC backlogs, when needed, and I'm not sure why that's a problem for users.

It's obvious why Slack wins for businesses: Because it gives businesses greater control and legibility over their employees' work habits and decision-making. DCC or any other P2P connection is anathema to this sort of control.

Users want different things. They want both plain text and rich text, and similarly, they want both plain chat and rich chat.

Oh, and aside from all of this, there is a working group [0] which publishes proposals for modernization of the IRC protocol. Adoption rates are low, but perhaps that should tell you something about what users actually want.

[0] https://ircv3.net/